1. Field of the Invention
The present invention relates to a cascade power system for extracting usable power from heat produced from the combustion of biomass, agricultural waste (such as bagasse,) municipal waste and other fuels. The present invention also relates to a cascade power system where heat is derived from a hot flue gas stream by mixing the stream with a precooled or partially spent flue gas stream so that the mixed flue gas stream has a desired lower temperature for efficient heating of the working fluid without causing undue stress and strain on the heat exchange unit.
More particularly, the present invention relates to a cascade power system for extracting usable power from heat produced from the combustion of biomass, agricultural waste (such as bagasse,) municipal waste and other fuels, where the system includes an energy extraction subsystem, a separation subsystem, a heat exchange subsystem, a heat transfer subsystem and a condensing subsystem, where the system forms a lean stream and a rich stream from a fully condensed incoming working fluid stream, vaporizes the lean and a rich streams from heat derived directly or indirectly from a heat source stream, converts thermal from the lean and rich streams to a usable form of energy forming a spent outgoing working fluid stream and condensing the outgoing working fluid stream to from the incoming working fluid stream and to methods for converting vaporizing a lean stream and a rich stream and extracting energy therefrom.
2. Description of the Related Art
Currently, the most efficient biomass fueled power plants have an overall plant efficiency of up to 20%, i.e., the net power output of these plants is up to 20% of the LHV (Lower Heating Value) of the combusted fuel. To achieve this level of efficiency, current biomass power plants require a very complicated combustion system which is comprised of a gasifier and a char combustor, and a power train that uses both a gas turbine and a steam power system, consequently, such systems are quite expensive.
Thus, there is a need in the art for a more efficient and simpler system for combusting a fuel such as biomass and converting a higher portion of its Lower Heating Value of the combusted fuel in to usable energy such as electricity.